Mouthpiece for transmitters.



L. STEINBERGER. MOUTHPIEOE FOR TRANSMITTERS.

Patented Jan. 12, 1915.

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LOUIS STEINBERGER, OF NEW YORK, N. Y.

MOUTHPIEGE FOR TRANSMITTER-S.

Specification of Letters Patent.

Patented Jan. 12, 1915.

Application filed October 18. 1910. Serial No. 587,719.

To all Whom it may concern:

Be it known that I, LOUIS Srmnnsnonn, a citizen of the United States,and a resident of the city of New York, borough of Brooklyn, in thecounty of Kings and State of New York, have inventeda new and 1mprovedMouthpiece for Transmitters, of which the following is a full, clear,and exact description.

My invention relates to mouthpieces for transmitters, and the particularpurpose thereof is to improve the acoustical properties of the device inits combination with the transmitter diaphragm by forming and disposingthe parts so as to concentrate, to a marked degree, the full volume ofsound waves, produced by the vibration of the vocal chords in speech, infront of the vibratory center of the transmitter diaphragm, and there,approximately within, a quarter of aninch of the surface oftheFdiaphragm suddenly expanding them to some degree and yet holdingthem to a relatively small central area of the diaphragm, in much thesame manner as if the lips of the person talking were held in closeunchanging proximity to the diaphragm, except that the portions of mydevice, corresponding to the lips, are somewhat smaller than lips andare circular so as to more effectively direct the sound waves intocontact with the most sensitive or central portion of the diaphragm.

A further object is to increase the me: chanical strength of themouthpiece.

To these ends I make the entire monthpiece comparatively thick andmassive and provide it with a single central sound passage of greatlyconstricted diameter at its inner end. and with an abruptly flaringcompartmentinto which the constricted end of said sound passage merges,said compartment b ing of substantially hemispherical shape and beingdisposed so that its walls extend abruptly radially in all directionsbeyond the constricted portion of sound passage. and curve thence moreand more toward the diaphragm about a central point located just slightlbehind the rear face of the center ol? the diaphragm. lhe opening of thecompartment toward the diaphragm small portion of the diaphragm,preferably about one-third its (liametrical dimension. This relativelysmall portion oi the diaphragm, being central, vibrates almost uniiormlythroughout its area with a maximum degree, or puretoned v bration; whilethe parts of the diaphragm nearer its periphery serve as a sort ofspring support for the vibratory central portion. It has been determinedthat sound waves, when led into direct contact, with this outer portion,lose their identity and strength and materially interfere with the purertoned vibrations of the central portion, and are responsible, to aconsiderable degree, for the subdued, faraway sound present in the usualtelephone conversation.

By providing my hemispherical chamber with smooth, uninterrupted wallsopening before only the central portion of the diaphragm and having itslarge annular edge brought into close proximity to the surface of thediaphragm for defining the pure toned vibratory central portion ofthediaphragm, and by having my sound passage entering it through a greatlyconstricted cen-' tral passage, I am enabled to retain nearly the fullforceof the voice concentrated upon the central portion of thediaphragm.

Among the several advantages sought to be attained by my invention arethe following: I. T 0 provide the mouthpiece with a small compartment asabove described, having the still smaller portion of said sound passagemerging thereinto, and to form these parts in a single integral bodyadapted to be attached to the ordinary phone structure in common use.11. To provide, directly around the compartment mentioned, a reducedthreaded portion for holding the mouthpiece 'firmly in position, and toform an annular shoulder disposed preferably substantially in a planecoinciding with the junction of said compartment and said sound passage.said shoulder .being formed at one end of said threaded portion andserving to retain the mouthpiece so that the hemispherical comi'iartmcnttherein will occupy its proper position relatively to the diz'iphragm asabove defined. 111. To provide a mouthpiece of the type above specifiedwith an annular rim integral with it in order to further increase itsmechanical strength. and at the same time to give it a more artisticdesign.

Reference is to be had to the accompanying drawings forming a part ofthis specification, in'which similar characters of reference indicatecorresponding parts in both the figures. v

Figure l is a substantially central vertical sectional view through myimproved mouthpiece mounted imposition as part of a transmitter, thisview being" slightly enlarged beyond the normal size of theparts inpractice; and Fig. 2is an inverted plan or rear view Tot the mouthpieceremoved from the transmitter.

' The transmitter casing is shown at 3 and the faceplate of thetransmitter at 4:, this face plate being provided with .a raised bead 5.

At 6 is the body member otthe mouth piece having generally a flaringformand provided at its outer end with rim"? integral with it and made thickand massive in order to possess considerable mechanical strength. Thebody member 6'is provided with a reduced threaded portion 8 pr0ducing anannular shoulder 9 atthe'outer end of said reduced threaded portion.[The body member 6 is further provided with a compartment or chamber 10having a substantially hemispherical wall, the lower boundaries of whichare coincident'with the end of said body member. The body niemberisprovided with a single sound passage which has-a very great diameter atits outer end and which tapers inwardly, and terminates in a decidedlyconstricted portion 12 at the point where it enters the hemisphericallyformed chamber 10.

preferablyvformed on curves which are substantially coincident witharcsof circles, the

centers of'which lie ina plane common with that of the point of junctureof the sound passage 11 and the hemispherically formed chamber 10, sothat he walls of the smaller portion of the sound passage, for a shortdistance beforethev reach the chamber 10, stand nearly parallel,producing a' sort of tube or nozzle which projects the sound Waves moreor less directly toward the cen tral portion of said chamber, only to bescattered as they abruptly enter said -chamber.-

phragm 13 and extends slightly into the hemispherical compartment 10.

My purpose in forming a single sound passage 11 and in giving said soundpassage theshape indicated, is to concentrate the sound waves in theportion 12 so as to give said sound waves the greatest possibleintensity as they enter the chamber 10. My

The Walls of this sound.passage,"lengthw1se of the same, are

passage wardlv from the present base of the chamber adjacent thesurface'of the diaphragm masses purpose in rendering the chamber 10"substantially hemispherical is to enable the sound waves, in proceedingfrom the portion 12 of the sound passage 11, to spread vout abruptlybefore reaching the dia-' terfere with each other .very greatly andtendto destroy each other. The fundamental tones, and the various overtones,become intermingled and produce a faulty'vibration of the diaphragmwhich consequently destroys the distinctness, so lamentably missing frompresent day telephones. This is especially true where the structure issuch as to leave any material portion of the diaphragm exposed toinfluence of directly projected sound waves, as has been above setforth, i v

In the combination of sound carrying parts illustrated in the structureshown, in-

terference of the sound waves is in great measure avoided. Theabru'ptness ot' entering thechamber 10 so scatters the waves, and thesmooth curved walls of the chamber so direct them, that they are largelyprevented from reaching and wasting their energy upon, and producirlg'ilse vibration of, portions of the diaphiagiii beyond the compass ofthecharnber, leaving those parts practically unaffected, except in apurely mechanicalsense, as a support for the pure toned vibratorycentral portion. For emphasizing the point involved, note that if thesound passage 11 were made of larger diameter in its portion 12, so thatits inner end was, say, of the size of the large opening of the chamber10, that the chamber were eliminated, and that the walls of thecontinued uninterruptedly outwith no appreciable or pronounced reductionin the siz of the vassa e. with no dis- I tinct shoulder or scatteringthe waves; the waves would be concentrated to a degree and would reachthe inner end of the passage in their direct and uninterrupted force. Amaterial part of them, being therefirst released, would m grate towardthe less sensitive peripheral port on of the diaphragm and interferewith the intended mechanical function of those portions, preventingtruevibration of the centralpart, and thus detract materially from theacoustical properties of the device. On the other lot my improvedstrength and volume of the sounds. proper distribution of the soundwaves hand; if the greatly restricted passage 12 were continued, withthe elimination of the chamber 10, the area of the dia ihragm affectedwould be entirely too small, so that sound waves migrating beyond itover the diaphragm would render the" resultant Waves unintelligible.Again, if the chamber 10 were enlarged so as to define a decidedlygreater central portion, or all of the diaphragm, much the same resultwould be obtained as in the first instance, though to a more markeddegree, the well defined central portion for receiving and transferringthe purer vibrations would be entirely lacking, and the consequentinterference between the relatively weak and the relatively strong wavesimpressed upon, and emanating from, the peripheral and central portions,respectively, would be unrestrained. The formation of sound carryingparts, as I have arrai'iged'them, however produces a maximum etl'ectupon a desirable extent of the sensitive central portion of thediaphragm and greatly reduces the tendency of the waves to migrateradially therefrom,

so that the central portion of the diaphragm I Will vibrate in trueresonance to the parent waves entering the mouthpiece. The inigratingwaves which succeed in reaching the peripheral portions of the diskbevond the confines of the chamber 10, are of insuiiicientintensityto,.of themselves, cause'any material vibration of those parts.

The foregoing facts, taken collectively and with the showing in thedrawings, indicate that the combination, and the relative proportions ofthe sound carrying parts, with the diaphragm, as assembled inmouthpiece, preserve all the By the from a single proximate point to arather small area near the proximate center of the diaphragm, I preservethe overtones in a fair degree. The net result is that my improvedmouthpiece both preserves, the volume of the sounds and maintains thetrue value of sounds of various kinds.

1 do not limit iiyself to the precise construction shown, for it will beseen that the essential characteristic of my invention is a I greatlyconstricted sound passage, continuing from a wide' flaring open end, andabruptly entering a dome-shaped chamber, said chamber itself being ofonly suilicient size, at its large open end, to encompass a relativelysmall, highly sensitive, portion of the diaphragm; the constrictedjiiassage abruptly entering the chamber, and the relation of the'chamberto the diaphragm effectively preventing deprecatory migration of soundwaves toward the periphery of the diaphragm. Neither do 1 limit mvselftobe used in the any particular material to though I construction of themouth-piece,

' open inner end of the chamber 10 is intended to he, itself, ofapproximately the diameter of the ordinary sound passage. I

Having thus described my invention, I

, claim as new and desire to secure by Letters Patent:

1. The combination with a telephone transmitter mechanism of usualconstruction comprising an apertured front *all and a diaphragmsupported behind said front wall substantially concentric with theaperture thereof, the diameter of the diaphragm being considerablygreater than that of the aperture, of it separately formed detachablemouthpiece having a part fitted into said aperture and extendingtherethrough into close proximity with the outer surface of thediaphragm, said part being hollowed out on its rear surface to form ahemispherical expansion chamber having uninterrupted and smooth Wallsterminating in close proximity to the surface of the diaphragm so as toencompass a central, sensitive, portion of the diaphragm relativelysmaller than the portion defined by the aperture of the front Wall, andthe mouthpiece being further formed with a single greatly constrictedsound passage opening substantiallv .centrally through the wall of thehemi-spherical chamber so that said wall extends abruptly radially inall directions from the end of said sound passage, and said soundpassage continuing outwardly into a Wide flaring open end, the walls ofsaid greatly constricted sound passage being formed on curves struckfrom centers substantially on the plane of the juncture of the soundpassage with the expaiisicn chamber so that portions of said soundpassage nearest said chamber are nearly parillei for giving a nozzlelike sha e to said sound passage, tending to project sound wavestl'ierefrom toward the center of the chamber, substantially as and forthe purposes set forth.

2. As an article of manufacture, a moutlr piece for telephonetransmitters comprising, a body of material having a reduced annularthreaded extension at one side thereof, adapted ior detachableengagement in the threaded aperture of a telephone transmitter casinsaid extension being hollowed out to form a conca ed expansicn chambersubstantially entirely within the extension hav ing uninterrupted andsmooth walls termitension, and said body pf material being In testimonywhereof I have signed my fuither'formed with a single greatly conname tothis specification in the presence 10 stricteci ts0und passage extendingt-hro igh of two-subscribing Witnesses. I

the main portion thereof and openlng into LQUISSTEINBERGER.

the expansion chamber,-s0 that the Wall of said chamber extends abruptlyradially in Withesses: 1

all directions from the end of the sound WALTON HARRIS01- I,, passage. vPHILIP D. Bananas..-

figieg 03 @his patent inay be obtained for five cents each. byadfizesing the Commissioner 9! Patent:,

Waihington, D. 0.

